A radio communication system, such as a cellular system, typically employs geographically dispersed transceiver sites to support subscriber units operating over a wide coverage area. Ordinarily, the sites are arranged such that each provides coverage for a particular geographic region, with some overlap in coverage. A subscriber unit interfaces with the radio communication system through a particular transceiver site, referred to herein as a server site or cell site. As a subscriber unit moves from one location to another, it may be advantageous to switch server affiliation from one site to another, in order to maintain a high-quality communication link. The process of switching server sites during an ongoing communication session is generally referred to in the art as hand-off or hand-over. The hand-off decision process usually involves the determination of the quality of signals between the subscriber unit and its server site, and the availability and suitability of other potential server sites that may be in communication range of the subscriber unit. The hand-off decision may be made using information gathered by the server site, information gathered by the subscriber unit, or a combination of both.
As subscriber units move about a system's coverage area, different loading conditions are created at the various server sites. To accommodate the subscriber units, communication resources, such as frequencies and time slots, must be made available as needed at each server site. When a subscriber unit requests resources that are unavailable, the results can include failure to establish a communication session, or even loss of an existing communication link. The problem of optimizing communication resource allocation is prevalent in multi-site systems.
It is desirable to enable a system to allocate communication resources to accommodate differing loading conditions as subscriber units move within a coverage area supported by different server sites. Preferably, such resource allocation is done in a manner that reduces dropped calls, and unacceptable delays when traversing between sites. Therefore, a new method for optimizing resource allocation in a radio communication system is needed.